Normal saline, antisera A, B & D, pricking needle (blood lancer); porcelin tile/glass slides, dropper, application sticks or tooth picks, glass marking pencil, cover slips, microscope and spirit swab.
PRINCIPLE Blood Group Test:
Blood group means the presence of antigen on RBCs which is genetically determined for speCIfic antibodies. RBCs contain different types of antigens (also known as agglutinogens) and plasma contains antibodies (also known as agglutinins). In order to detect blood group, RBCs are allowed to react with serum which contains corresponding agglutinins and so agglutination occurs. Saline suspension of red cells is mixed with antisera A, antisera B, antisera D and agglutination looked for, presence or absence of agglutination may be confirmed by microscope examination of the sample.
|Phenotype of blood group||Geno type of blood group||antigens on RBC (Agglutinogen)||Antibody in serum
DIFFERENT TYPES OF BLOOD GROUP TESTING:
- Conventional tube test
- Slide tests
- Reverse grouping in which the serum of the patients Is used Instead of RBC. it decrease the error of blood grouping.
- Agglutination can be compared with saline mixture of cells which is taken as control? Under low power of microscope RBCs are together in clumps.
- With naked eye agglutination of RBCs appears as a coarse separation of red cells in isolated clumps (red precipitates of cells).
- Mix the cells with antsiera by using separate application sticks or by rocking the tile or glass slide to and fro.
- Add one drop of saline suspension of cells with the help of dropper to different antisera without touching any antisera with dropper.
- Mark A, B, D and S near different pits on the tile (Figure 20) or take two slides and mark A and B on one slide and D and S on other with the help of glass marking pencil as shown in Figure 21.
- 1.Take 2 ml of normal saline in a watch glass or one ml in a pit of porcelin tile
- Add a drop of blood, after pricking the finger in all aseptic conditions in saline.
- Now put a drop of antisera A, antisera B, and antisera D in the pits or on the slide according to the respective markings from antisera vials.
- Add two drops this saline suspension of cells where you have marked S on tile or on glass slide. It will act as a control to compare with agglutinated cells.
- Wait for 10 minutes and examine the mixture for agglutination (clumping of RBCs) with naked eye, if required confirm under low power of microscope.
- By rocking the tile or slide agglutinated cells do not make uniform/homogenous mixture of cells.
- Blood group is determined as indicated in the table give below.
- Tile or slide should be clean and dry.
- There should be no intermixing of the mixture put on different places on tile or on slide.
- Any doubt in agglutination must be confirmed under low power of microscope. 4. Rotate slides gently to avoid mixing of the sera.
- Mixing of the blood and serum should be quick enough to avoid coagulation.